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Originally Posted by Peregrino
OK - I'm sacrificing myself for the greater good. I don't normally throw myself on live grenades but this one I've got to see. What's confusing me is the definition of hardness. Rockwell #s aside, I thought hardness (as a factor in edge holding ability) was a function of % of carbon in the steel, the heat treat, and the resulting grain size and density of the carbides. Softer steel = fewer carbide crystals in the iron matrix. (Assuming a quality heat treat with controlled grain size/growth that doesn't leave the steel brittle and prone to cracking.) Since the exposed carbides (ideally troosite after martensite is converted during tempering) along the edge (earlier lecture on S30V) do the cutting, and resist wear better than the iron matrix, how is a softer steel going to hold a better edge? I've been able to get softer steels sharpened with less work and (without an electron microscope to make the comparison) they seemed as sharp as the harder steels, but heavy use - dressing game, cutting meat, hides, leather, etc. - required frequent touchups to maintain the edge. Every time I've used a cutting tool (machete, axe, sickle, sythe, etc.) it's been a softer steel and it always lost its edge with use. I didn't pay much attention to the particular steels used because they were cheap work implements often locally manufactured from scrounged materials with more art than science. On the other hand my Yarborough knife still has the factory edge and it will still shave anything that'll hold still long enough. Am I reading too much into this? Inquiring minds want to know -  Peregrino |
Looks like we better figure out simple knife shop and user definable hardness in tool steels before we go any farther and I will do that later.
There are knives harder than the Yarborough that will not hold an edge as long.
The answer to this can be found in the preceding text.
Edited to add:
Or maybe not, after review I note it was alluded to it but not explained.
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